A Nottingham Forest fan will cycle from Land's End to John O'Groats to support his girlfriend, who was born with duplex kidneys.
Sarah Biddle's condition is thought to have been caused by fallout from the Chernobyl Disaster, in 1986, which drifted from the former Soviet Union.
Jonny Heald hopes to complete the 1,000-mile (1,609km) ride within 63 hours, starting on Saturday.
The money raised will go towards finding kidney donors.
Health experts believe that plumes of fallout from the stricken Chernobyl Nuclear Power Plant, in Ukraine, affected a number of unborn babies a year after it exploded.
Farms in North Wales and the Lake District were also badly affected.
A duplex kidney means that part, or all, of a kidney is duplicated
Ms Biddle, who is from the West Midlands, has only 40% functionality in her organs and may also need a transplant in the future.
"She went in for an operation over Christmas and I thought why not raise a bit of money," said Mr Heald.
"I foolishly agreed after a night in the pub with friends."
Mr Heald is raising money for Kidney Research UK and said the money would help support families and investigate alternative treatment methods.
The teacher said all of his training for the challenge had been in the gym.
"I only picked up my bike yesterday," said Mr Heald.
"I've not ridden a bike since I was 12, so, it's going to be an interesting couple of days."
Mr Heald, who is attempting the challenge along with a Derby County fan, has raised £534.64, so far.